If you're tired of waiting in long lines at food trucks, a new state regulation might have just made the wait shorter.

As of last week, it's legal for proprietors to post a flat-rate price, such as $10, for a meal with sales tax included. The idea is to eliminate adding the sales tax at the point of purchase, which slows down the line as customers fumble for change or sales associates count it out.

"I am all for this new law because it makes it so much easier for the customer and easier for us not having to carry around extra change," said Joan Miller, owner and operator of the Hot Diggity hot dog cart in Mill Valley.

"The point was to streamline the process for everybody," said Brian Miller of the state Board of Equalization, the public agency charged with the administration of taxes and fee collection. "The ... number of food trucks in California has grown substantially and we wanted to make it easier on everybody."

The number of trucks permitted to sell food in Marin has zoomed over the years, going from 14 to 41 between 2008 and July 2012 and jumping to 124 since then, according to Rebecca Ng of Marin County Environmental Health Services. Mobile vendors can be found at the Marin Country Mart, Novato's Vintage Oaks and farmers markets at the Marin Civic Center and downtown San Rafael, among other locations.

"The food truck has space for a limited number of people, so you have to be very fast in service," said Thomas Odermatt, owner of Roli Roti, a rotisserie chicken truck at the Novato Farmers Market. He has been offering his gourmet chicken at the market for 12 years.

"You cannot have multiplication and complicated calculations, so we calculate everything with the sales tax and deduct the sales tax later on," Odermatt said.

'Less of a hassle'

Before now, food truck operators like Odermatt had to post signs saying the tax is included in prices or add the tax to the listed price, leading to different prices based on where the truck is parked when the sale is made. Now, they can charge one price no matter where they sell it and calculate how much they owe when they pay their sales tax.

"If they didn't have a sign we presumed tax was not included. For example, if the sales tax rate was 10 percent, and the list price for a sandwich was $5 we would have presumed automatically it was $5.50 after tax. Now if we see a $5 menu price, we presume $4.55 is the taxable selling price, and the other 45 cents is the sales tax collected from the customer," said Yating Campbell of the Board of Equalization.

"I see it both ways. For the operator it's less of a hassle so he can focus more on the food safety," Odermatt said.

"But the customer might not realize they don't have to pay tax on top of it. It's a communication issue. We make it very clear all the prices include the sales tax," Odermatt said.

"The customer is used to paying tax so if they see the higher price they may be deterred from buying," said Brett Sibley, co-owner of Edgewater Fish Company and the food truck the Crab Lab.

The Crab Lab is one of the food trucks to be found at the mobile food event at Larkspur's Marin Country Mart. That event runs from 11 a.m. to 3 p.m. every Sunday. The Vintage Oaks event runs from 5 to 9 p.m. behind the Old Navy store on Thursdays.

"I think food trucks in general are happy to have greater clarity on how to handle sales tax," said Off the Grid founder and chief executive Matt Cohen. Off the Grid works with 175 food trucks and 29 events as far south as Sunnyvale and as far east as Dublin. It is the company behind the Country Mart and Vintage Oaks events.

Cohen added, "More broadly, anything that helps get tax money where it needs to go more expeditiously is nothing but positive for the future success of the street food industry as a whole."

Contact Janis Mara at 415-382-7207. McClatchy Tribune News Service contributed to this report.